/*
 * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#ifndef OSSL_INTERNAL_LIST_H
#define OSSL_INTERNAL_LIST_H
#pragma once

#include <string.h>
#include <assert.h>

#ifdef NDEBUG
#  define OSSL_LIST_DBG(x)
#else
#  define OSSL_LIST_DBG(x) x;
#endif

/* Define a list structure */
#define OSSL_LIST(name) OSSL_LIST_##name

/* Define fields to include an element of a list */
#define OSSL_LIST_MEMBER(name, type)                                           \
  struct                                                                       \
  {                                                                            \
    type *next, *prev;                                                         \
    OSSL_LIST_DBG(struct ossl_list_st_##name *list)                            \
  } ossl_list_##name

#define DEFINE_LIST_OF(name, type)                                             \
  typedef struct ossl_list_st_##name OSSL_LIST(name);                          \
  struct ossl_list_st_##name                                                   \
  {                                                                            \
    type *alpha, *omega;                                                       \
    size_t num_elems;                                                          \
  };                                                                           \
  static ossl_unused ossl_inline void ossl_list_##name##_init(OSSL_LIST(name)  \
                                                              * list)          \
  {                                                                            \
    memset(list, 0, sizeof(*list));                                            \
  }                                                                            \
  static ossl_unused ossl_inline void ossl_list_##name##_init_elem(type *elem) \
  {                                                                            \
    memset(&elem->ossl_list_##name, 0, sizeof(elem->ossl_list_##name));        \
  }                                                                            \
  static ossl_unused ossl_inline int ossl_list_##name##_is_empty(              \
      const OSSL_LIST(name) * list)                                            \
  {                                                                            \
    return list->num_elems == 0;                                               \
  }                                                                            \
  static ossl_unused ossl_inline size_t ossl_list_##name##_num(                \
      const OSSL_LIST(name) * list)                                            \
  {                                                                            \
    return list->num_elems;                                                    \
  }                                                                            \
  static ossl_unused ossl_inline type *ossl_list_##name##_head(                \
      const OSSL_LIST(name) * list)                                            \
  {                                                                            \
    assert(list->alpha == NULL || list->alpha->ossl_list_##name.list == list); \
    return list->alpha;                                                        \
  }                                                                            \
  static ossl_unused ossl_inline type *ossl_list_##name##_tail(                \
      const OSSL_LIST(name) * list)                                            \
  {                                                                            \
    assert(list->omega == NULL || list->omega->ossl_list_##name.list == list); \
    return list->omega;                                                        \
  }                                                                            \
  static ossl_unused ossl_inline type *ossl_list_##name##_next(                \
      const type *elem)                                                        \
  {                                                                            \
    assert(elem->ossl_list_##name.next == NULL                                 \
           || elem->ossl_list_##name.next->ossl_list_##name.prev == elem);     \
    return elem->ossl_list_##name.next;                                        \
  }                                                                            \
  static ossl_unused ossl_inline type *ossl_list_##name##_prev(                \
      const type *elem)                                                        \
  {                                                                            \
    assert(elem->ossl_list_##name.prev == NULL                                 \
           || elem->ossl_list_##name.prev->ossl_list_##name.next == elem);     \
    return elem->ossl_list_##name.prev;                                        \
  }                                                                            \
  static ossl_unused ossl_inline void ossl_list_##name##_remove(               \
      OSSL_LIST(name) * list, type * elem)                                     \
  {                                                                            \
    assert(elem->ossl_list_##name.list == list);                               \
    OSSL_LIST_DBG(elem->ossl_list_##name.list = NULL)                          \
    if (list->alpha == elem)                                                   \
      list->alpha = elem->ossl_list_##name.next;                               \
    if (list->omega == elem)                                                   \
      list->omega = elem->ossl_list_##name.prev;                               \
    if (elem->ossl_list_##name.prev != NULL)                                   \
      elem->ossl_list_##name.prev->ossl_list_##name.next                       \
          = elem->ossl_list_##name.next;                                       \
    if (elem->ossl_list_##name.next != NULL)                                   \
      elem->ossl_list_##name.next->ossl_list_##name.prev                       \
          = elem->ossl_list_##name.prev;                                       \
    list->num_elems--;                                                         \
    memset(&elem->ossl_list_##name, 0, sizeof(elem->ossl_list_##name));        \
  }                                                                            \
  static ossl_unused ossl_inline void ossl_list_##name##_insert_head(          \
      OSSL_LIST(name) * list, type * elem)                                     \
  {                                                                            \
    assert(elem->ossl_list_##name.list == NULL);                               \
    OSSL_LIST_DBG(elem->ossl_list_##name.list = list)                          \
    if (list->alpha != NULL)                                                   \
      list->alpha->ossl_list_##name.prev = elem;                               \
    elem->ossl_list_##name.next = list->alpha;                                 \
    elem->ossl_list_##name.prev = NULL;                                        \
    list->alpha = elem;                                                        \
    if (list->omega == NULL)                                                   \
      list->omega = elem;                                                      \
    list->num_elems++;                                                         \
  }                                                                            \
  static ossl_unused ossl_inline void ossl_list_##name##_insert_tail(          \
      OSSL_LIST(name) * list, type * elem)                                     \
  {                                                                            \
    assert(elem->ossl_list_##name.list == NULL);                               \
    OSSL_LIST_DBG(elem->ossl_list_##name.list = list)                          \
    if (list->omega != NULL)                                                   \
      list->omega->ossl_list_##name.next = elem;                               \
    elem->ossl_list_##name.prev = list->omega;                                 \
    elem->ossl_list_##name.next = NULL;                                        \
    list->omega = elem;                                                        \
    if (list->alpha == NULL)                                                   \
      list->alpha = elem;                                                      \
    list->num_elems++;                                                         \
  }                                                                            \
  static ossl_unused ossl_inline void ossl_list_##name##_insert_before(        \
      OSSL_LIST(name) * list, type * e, type * elem)                           \
  {                                                                            \
    assert(elem->ossl_list_##name.list == NULL);                               \
    OSSL_LIST_DBG(elem->ossl_list_##name.list = list)                          \
    elem->ossl_list_##name.next = e;                                           \
    elem->ossl_list_##name.prev = e->ossl_list_##name.prev;                    \
    if (e->ossl_list_##name.prev != NULL)                                      \
      e->ossl_list_##name.prev->ossl_list_##name.next = elem;                  \
    e->ossl_list_##name.prev = elem;                                           \
    if (list->alpha == e)                                                      \
      list->alpha = elem;                                                      \
    list->num_elems++;                                                         \
  }                                                                            \
  static ossl_unused ossl_inline void ossl_list_##name##_insert_after(         \
      OSSL_LIST(name) * list, type * e, type * elem)                           \
  {                                                                            \
    assert(elem->ossl_list_##name.list == NULL);                               \
    OSSL_LIST_DBG(elem->ossl_list_##name.list = list)                          \
    elem->ossl_list_##name.prev = e;                                           \
    elem->ossl_list_##name.next = e->ossl_list_##name.next;                    \
    if (e->ossl_list_##name.next != NULL)                                      \
      e->ossl_list_##name.next->ossl_list_##name.prev = elem;                  \
    e->ossl_list_##name.next = elem;                                           \
    if (list->omega == e)                                                      \
      list->omega = elem;                                                      \
    list->num_elems++;                                                         \
  }                                                                            \
  struct ossl_list_st_##name

#endif
